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Abstract Background Corpus luteum (CL) regression is known to occur as two parts; functional regression when steroidogenesis declines and structural regression when apoptosis is induced. Previous studies suggest this process occurs by the production of luteolytic factors, such as tumour necrosis factor-alpha (TNF-alpha). Methods We examined TNF-alpha, TNF-alpha receptors (TNFR1 and 2) and steroidogenic acute regulatory (StAR) protein expression during CL regression in albino Wistar rats. CL from Days 16 and 22 of pregnancy and Day 3 post-partum were examined, in addition CL from Day 16 of pregnancy were cultured in vitro to induce apoptosis. mRNA was quantitated by kinetic RT-PCR and protein expression examined by immunohistochemistry and Western blot analyses. Results TNF-alpha mRNA increased on Day 3 post-partum. TNFR were immunolocalized to luteal cells, and an increase in TNFR2 mRNA observed on Day 3 post-partum whilst no change was detected in TNFR1 mRNA relative to Day 16. StAR protein decreased on Day 3 post-partum and following trophic withdrawal but no change was observed following exogenous TNF-alpha treatment. StAR mRNA decreased on Day 3 post-partum; however, it increased following trophic withdrawal and TNF-alpha treatment in vitro. Conclusion These results demonstrate the existence of TNFR1 and TNFR2 in rat CL and suggest the involvement of TNF-alpha in rat CL regression following parturition. Furthermore, decreased StAR expression over the same time points was consistent with the functional regression of the CL.

Commensal plants and animals have long been used to track human migrations, with Rattus exulans (the Pacific rat) a common organism for reconstructing Polynesian dispersal in the Pacific. However, with no knowledge of the homeland of R. exulans, the place of origin of this human-commensal relationship is unknown. We conducted a mitochondrial DNA phylogeographic survey of R. exulans diversity across the potential natural range in mainland and Island Southeast Asia in order to establish the origin of this human-commensal dyad. We also conducted allozyme electrophoresis on samples from ISEA to obtain a perspective on patterns of genetic diversity in this critical region. Finally, we compared molecular genetic evidence with knowledge of prehistoric rodent faunas in mainland and ISEA. We find that ISEA populations of R. exulans contain the highest mtDNA lineage diversity including significant haplotype diversity not represented elsewhere in the species range. Within ISEA, the island of Flores in the Lesser Sunda group contains the highest diversity in ISEA (across all loci) and also has a deep fossil record of small mammals that appears to include R. exulans. Therefore, in addition to Flores harboring unusual diversity in the form of Homo floresiensis, dwarfed stegodons and giant rats, this island appears to be the homeland of R. exulans. [ABSTRACT FROM AUTHOR]

We have shown previously that intraocular elevation of cAMP using the cAMP analog 8-(4-chlorophenylthio)-cAMP (CPT-cAMP) failed to promote axonal regeneration of axotomized adult retinal ganglion cells (RGCs) into peripheral nerve (PN) grafts but significantly potentiated ciliary neurotrophic factor (CNTF)-induced axonal regeneration. Using the PN graft model, we now examine the mechanisms underlying spontaneous and CNTF/CPT-cAMP-induced neuronal survival and axonal regrowth. We found that blockade of the cAMP pathway executor protein kinase A (PKA) using the cell-permeable inhibitor KT5720 did not affect spontaneous survival and axonal regeneration but essentially abolished the CNTF/CPT-cAMP-induced RGC survival and axonal regeneration. Blockade of CNTF signaling pathways such as phosphotidylinositol 3-kinase (PI3K)/akt by 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY294002), mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) by 2-(2-diamino-3-methoxyphenyl-4H-1-benzopyran-4-one (PD98059), or Janus kinase (JAK)/signal transducer and activators of transcription (STAT3) by tyrphostin AG490 also blocked the CNTF/CPT-cAMP-dependent survival and regeneration effects. PKA activity assay and Western blots showed that KT5720, LY294002, and PD98059 almost completely inhibited PKA, PI3K/akt, and MAPK/ERK signal transduction, respectively, whereas AG490 substantially decreased JAK/STAT3 signal transduction. Intraocular injection of CPT-cAMP resulted in a small PKA-dependent increase in CNTF receptor α mRNA expression in the retinas, an effect that may facilitate CNTF action on survival and axonal regeneration. Surprisingly, in the absence of CNTF/CPT-cAMP, LY294002, PD98059, and AG490, but not KT5720, significantly enhanced spontaneous RGC survival, suggesting differential roles of these pathways in RGC survival under different conditions. Our data suggest that CNTF/ CPT-cAMP-induced RGC survival and axonal regeneration are a... [ABSTRACT FROM AUTHOR]

Morphological and genetic analyses of Eonycteris spelaea from 15 islands along the Banda Arc, from Sumatra to Timor and including Kalimantan and Sulawesi, revealed considerable divergence between islands and geographical patterning. On the basis of both morphology and genetics, the populations on the large islands of Greater Sunda (Sumatra, Java, Kalimantan and Sulawesi) are generally distinct from one another and from those on the islands in Nusa Tenggara (Lombok to Timor), which form a more cohesive cluster. These differences may be the result of the Nusa Tenggara populations having been colonized more recently than those on the Greater Sunda, and probably from a single source. All biological measures of the relationships between island populations are positively associated with the extent of the sea-crossing between them, indicating the sea is an important barrier to movement. Multivariate analyses show the presence of a marked trend for body size to increase from west to east. However, individuals from Kalimantan are not consistent with this trend, being smaller than predicted, and on the two outer Banda Arc islands of Sumba and Timor animals are a little larger than predicted from the longitudinal trend. These differences could be due to the relative isolation of these populations or differing environmental conditions. There is also a negative relationship between body size and island area, but this is confounded by the longitudinal trend. No significant longitudinal trends in the genetic data were detected and the trend in body size may be an adaptive response to an environmental cline that is known to occur in this region. © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 79, 511–522. [ABSTRACT FROM AUTHOR]

Commensal plants and animals have long been used to track human migrations, with Rattus exulans (the Pacific rat) a common organism for reconstructing Polynesian dispersal in the Pacific. However, with no knowledge of the homeland of R. exulans, the place of origin of this human-commensal relationship is unknown. We conducted a mitochondrial DNA phylogeographic survey of R. exulans diversity across the potential natural range in mainland and Island Southeast Asia in order to establish the origin of this human-commensal dyad. We also conducted allozyme electrophoresis on samples from ISEA to obtain a perspective on patterns of genetic diversity in this critical region. Finally, we compared molecular genetic evidence with knowledge of prehistoric rodent faunas in mainland and ISEA. We find that ISEA populations of R. exulans contain the highest mtDNA lineage diversity including significant haplotype diversity not represented elsewhere in the species range. Within ISEA, the island of Flores in the Lesser Sunda group contains the highest diversity in ISEA (across all loci) and also has a deep fossil record of small mammals that appears to include R. exulans. Therefore, in addition to Flores harboring unusual diversity in the form of Homo floresiensis, dwarfed stegodons and giant rats, this island appears to be the homeland of R. exulans. [ABSTRACT FROM AUTHOR]